In an ideal environment for listening to stereo reproduction the louspeakers would be located symmetrically and the listener would be located symetrically relative to the two loudspeakers, i.e. on a center line between them. These ideals are seldom realized in practice; often the speaker environment is assymetric and/or the listening location is asymmetric relative to the speakers, so that inter-channel differences in sound path lengths and other acoustic properties detract from optimal perception of the stereophonic sound. Loudness unbalance can be corrected by the usual balance control provided, and EQ (amplitude versus frequency equalization) may be balanced if EQ capability is available independently in each channel. Unbalanced time delays due to the different acoustic path lengths in the two channels can be compensated by introducing additional time delay in the channel having the shorter acoustic path. Other available sound processing techniques may be applied in a particular manner in each channel to optimize a particular asymmetric listening location.
Setting these various compensations for optimal stereo listening as perceived at a particular location can be inconvenient and time-consuming. When the listening location changes, a new setup is usually required.
A remote control unit with the capability of controlling the necessary parameters independently on each channel is very beneficial since adjustment can be made by the listener from the listening location. Even with the remote control, making the necessary readjustments each time one relocates is tedious, and the difficulty increases sharply with the level of quality sought due to the increased number of audio parameters which must be adjusted and optimized each time.
For serious listeners in the field of high quality stereo, this is an unsolved problem: there is a growing and unfulfilled need for a user-friendly system for optimizing the stereo adjustments for particular listening locations.